1. Technical Field
The present invention relates to optical elements, optical modules, and optical transmission devices.
2. Related Art
Surface-emitting type semiconductor lasers have a characteristic in that their optical output changes according to the surrounding temperature. For this reason, an optical module using a surface-emitting type semiconductor laser may be provided with an optical detection function that detects a part of laser light emitted from the surface-emitting type semiconductor laser to monitor its light output value. For example, an optical detection device such as a photo diode may be provided on a surface-emitting type semiconductor laser, whereby a part of laser light emitted from the surface-emitting type semiconductor laser can be monitored within the same device. For example, such a technique is described in JP-A-2000-114658.
Also, photonic ICs are being developed for conducting two-way communications with a single optical fiber by using a structure similar to the aforementioned structure in which a photodiode is laminated on a surface-emitting type semiconductor laser. For example, such a technology is described in J-A-11-4046.